Integrated semiconductor devices are typically constructed en masse on a wafer of silicon or gallium arsenide. Each device generally takes the form of an integrated circuit (IC) die. If the die is to be encapsulated in a plastic package, it is first bonded to the die-mounting paddle of a leadframe which is attached to other leadframes in a leadframe strip. The wire attachment pads on the die are connected with their corresponding leads on the leadframe with aluminum or gold wire during a wire bonding process, following which the die is coated with a protective polyimide film. Finally, the die is encapsulated in plastic and the plastic-encapsulated chip undergoes a trim and form operation which separates the interconnected packages on the leadframe strip into individual entities and bends (forms) the leads of each package. The package is then recognizable as an IC "chip". The operation for manufacturing plastic-encapsulated packages is highly automated, allowing high quality and low cost.
The encapsulation of dies in ceramic packages is a more complicated and, generally, much less automated process. FIG. 1 is an isometric view of a typical ceramic, side-brazed, dual inline package. Such a package, consisting of a main body 11 and a lid 12, is typically expensive, costing an average of $3.75 per 16-pin package. The lid 12, manufactured from a nickel-gold alloy, contributes approximately 20% to the cost of the package. The main body 11 is formed from three ceramic layers. The first layer 13, contains a gold-plated ground plane 14, which is connected to the grounded pin of the package. The second layer 15 contains numerous gold-plated traces 16 which serve as the package bonding pads and each of which is interconnected with its associated package pin. The third layer 17 has a gold-plated border 18 surrounding the die installation cavity 19. A semiconductor die will be bonded to the ground plane 14 within the die installation cavity, and the bonding pads of the die are interconnected with the bonding pads formed by the ends of traces 16 of the package body with gold wire during a wire-bonding operation.
Still referring to FIG. 1, the process of hermetically sealing the lid 12 to main body 11 proceeds by clamping the lid 12, which is coated with a solder border 20, in position over the die installation cavity, following which the entire package is subjected to a solder reflow operation. During reflow, which lasts some 25 minutes, the solder border 19 on the lid melts and fuses with the gold-plated border 18 on body 11. Each package must be individually retrieved from and returned to process trays, since the leads are not joined with those of other packages in a leadframe strip. In addition, each lid 12 must be individually clamped to its associated package body.